While I've never claimed to be the R&T authority on pastries and baked goods—that'd be colleague John Lamm—I can spot a "have your cake and eat it too" scenario from a long way off. Like this pair of impressive rear-drive V-8 sports sedans, for instance. The , fresh off its Ponton-fender 2009 restyle with a flinty stare from its rhomboid headlights and chiseled hood, is the better known player. The upstart? The new , with 5.6 liters of direct-injected brawn, sheet-metal curves seemingly cultured in a petri dish and a lavishly trimmed interior. Each can fire off a low 13-second quarter-mile pass without even trying all that hard, and then remove its track cleats and absorb miles of Interstate with the comfort of expensive slip-on loafers.

And in the twisties? Like overfed tabbies that slalom through the coffee-table legs when the Fancy Feast is served, their agility belies their 2-ton mass. Both are equipped with Sport packages, the nonadjustable chassis calibrations somewhat firmer (and augmented with rear-wheel steering), the offering two damping rates with its Airmatic air-spring suspension. Each is filled to its power-operated moonroof with high-tech infotain-ment and safety equipment (the options per car here average $10,910!), some of it useful, some of it annoying...like a gnat circling your face that you can't quite swat away.

Measured by performance and exterior dimensions, the M56 and E550 are peas in a sports-sedan pod, yet they're very different cars in execution, feel and philosophy, which is why we do comparison tests in the first place and not just list tables of specifications and acceleration numbers. So with this in mind, National Editor Mike Monticello, videographer Jay McNally, John Lamm and I set out for two days of evaluation, circling San Diego County's Lake Cuyamaca, ridge-running along the Sunrise Highway and ultimately having some good Italian food in the touristy apple-orchard enclave of Julian. A man's gotta eat. Here's what we found.

Mercedes-Benz E550Points: 378.8 |

From the first press of its accelerator pedal, the E550 presents itself as the kinder, gentler sports sedan—if anything with 382 bhp could be characterized as kind and gentle. Its 5.5-liter 4-cam V-8 revs with an authoritative V-8 throb, but it's as if each exhaust pulse is softly attenuated by velvet-lined tailpipes. Its air-spring suspension firms automatically with a sudden steering input (or the press of a console-mounted button), but speed bump and chuckhole absorption remains world-class. And while styling is highly subjective, the staff consensus is this ninth-generation E-Class goes for sophistication with sporty overtones, its body an interplay of concave and convex surfaces tied together with bold creases.

So why, you ask, is this Benz on the second step of the podium? Well, it really goes back to the ride/handling compromise and where your priorities lie, because while the E550 is the M56's equal in a straight line (despite its 38-bhp deficit), it's Salieri to Infiniti's Mozart in driving fun when you're in the wring-it-out mode. Blame it on steering that feels increasingly rubbery as lateral g's build, the transmission's slightly lethargic kickdown reaction to heavy throttle, a bit more body roll and, as the limit is approached, understeer from front tires that are considerably narrower than the rears (245s versus 265s).

But let's keep this in perspective, as the Merc's structure feels drum-tight, the engine is smoother and endowed with a broader powerband, and there's less racket transmitted through the tires and suspension on rough roads. So, at a brisk 7/10ths pace, the Benz suddenly becomes at least as—if not more—rewarding. Said Monticello, "Its smoother ride and less aggressive throttle tip-in gives it a less frantic nature than the M56—perfect for calming you down on your drive home from a long day at the office."

Inside, the Merc's dash styling is painted in contemporary, angular strokes that find a happy middle ground between conservatism and actual flair...a little boring for some, but it should stand the test of time. The optional Multicontour driver's seat is great, "Exceptionally comfortable," Monticello said, "plus it offers considerably more lateral support than the M56's." But we could both do without the Drive Dynamic feature (defeatable, thankfully) that inflates and deflates the side bolsters in response to cornering loads. If they were any more touchy-feely with our finely calibrated buttocks, we'd file a sexual harassment suit. And then there's the COMAND interface, which works well in most situations yet requires multiple visits to the owners manual, versus the Infiniti's significantly more intuitive setup and eye-friendly graphics. And on the subject of learned behavior, the E550 first-time user will attempt to signal with the cruise control stalk a couple of times.

So that's the Mercedes...polished, comfortable, composed but just flat-out less sporty. We suspect its marketplace positioning is wholly intentional, what with buyers having the option of the vastly more driver-focused (and expensive) E63 AMG.

Infiniti M56Points: 386.6 |

Toss a victory wreath on the M56's hood, but it was a hard-fought battle and the M56 is not without a few flesh wounds. As mentioned before, the performance categories were nearly a dead heat (and 4.6 sec. to 60 mph is plenty quick by anyone's standard), right down to braking distances within mere feet of each other. But scan through our ratings chart and the scars emerge. The Sport-package seats were, surprisingly, long on cush but short on lateral support. The ride quality took a hit, predictably, with the big 20-in. wheels and firmly calibrated shocks imposing their will on ride motions. And exterior styling was rated a little too ambitious, the consensus being that the fender forms are too exaggerated and the car looks tall and narrow, especially when parked next to the Benz. It's as if the G37 sedan's handsome good looks just don't quite scale up to a larger car.

But uncork the 5.6-liter direct-injected V-8 (slightly peakier and throatier than the Benz's) and point the M56's furrowed brow down your favorite twisty road, and the situation improves considerably. Twist the Drive Mode Selector knob to Sport and there's right-now throttle response and higher effort from the quick-ratio steering. Large steering-wheel-mounted paddles summon crisp shifts from the 7-speed automatic, the gearbox auto-blipping the throttle expertly when changing down. The uprated Sport brakes don't mess around either, with a firm and reassuring pedal and optional R Spec friction linings. The only real annoyance is what Infiniti calls Active Trace Control (part of the Technology package) that essentially trail-brakes for you to increase the load on the front wheels, and can modulate engine torque and selectively brake individual wheels in quick transitional maneuvers. Said Monticello, "It's very unnerving when the car brakes harder than you were braking, and sometimes after you've already come off the brakes." Fortunately, it intervenes less when in the Sport mode, but it can't be defeated entirely.

Underperforming seat bolsters aside, the M56's interior is great, with beautiful wood, metallic accents and leather, all arranged with a sweep and form that's almost Italianate in expression. The electroluminescent gauges are bright and have interesting faces with a knurled texture, and the infotainment interface is among the best in the business in terms of ease of use and intuitive operation. "I especially dig the M56's upper center stack that's almost horizontal," said Monticello, "kind of like a computer keyboard or a large cell phone." Rear seat passengers aren't neglected either; while it's about a wash between the two in terms of space, the M56's rear seats are better contoured and more comfortably padded than the E550's.

So in the end, if we were racing in the Pikes Peak Premium Sports Sedan class, we'd belt into the M56 for the hillclimb record attempt. And for the drive back from Colorado Springs to our Newport Beach offices? Probably the E550. But in the final tally, the Infiniti's blend of responsiveness, luxury, performance and style (the interior's, at least) was enough to notch a fiercely contested win.